was wondering if anyone can give me some ideas how best to structure an essay comparing the structure and functioning of epithelia cells in the epidermis and of the small intestine ie a logical order. This is my weakest area ie essay writing so would appreciate any ideas.

Comparison itself: Organize your comparison logically in broad section (common/different or structure1:structure2:...). The important point is not necessarily HOW you divide, but that the division is coherent along all the text and have an easy to perceive underpinning logic. In any case discuss the meaning of the difference/similarity wrt to the function of the cell.

Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)